Thermal detection systems, methods, and devices

ABSTRACT

Systems, methods, and devices for thermal detection. A thermal detection device includes a visual sensor, a thermal sensor (e.g., a thermopile array), a controller, a user interface, a display, and a removable and rechargeable battery pack. The thermal detection device also includes a plurality of additional software and hardware modules configured to perform or execute various functions and operations of the thermal detection device. An output from the visual sensor and an output from the thermal sensor are combined by the controller or the plurality of additional modules to generate a combined image for display on the display.

RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional PatentApplication No. 61/678,692, filed Aug. 2, 2012, the entire content ofwhich is hereby incorporated by reference.

BACKGROUND

This invention relates to thermal detection systems, methods, anddevices. Thermal detection devices, such as thermal detectors, are usedby professionals in a variety of industries to assess temperatures ofobjects within a field-of-view (“FOV”) of the thermal detector. Theassessment of the scene includes, for example, generating a multi-coloror multi-level contrast image of the scene and determining temperaturemeasurements of the scene.

SUMMARY

Although thermal detection devices are known, many of the devices areprohibitively expensive due to, among other things, the detectors beingused for thermal detection. For example, many thermal imagers use ahigh-resolution microbolometer as a detector. The use of high-resolutionmicrobolometers in thermal imagers allows the thermal imagers togenerate accurate thermal images of a scene, but also significantlyincreases the cost of the thermal imagers.

This invention provides thermal detection devices which are configuredto generate relative or absolute temperature representations of a scene.In one embodiment, the invention provides a thermal detection devicethat includes a visual sensor, a thermopile array, a controller, a userinterface, a display, and a removable and rechargeable battery pack. Thethermal detection device also includes a plurality of additionalsoftware or hardware modules configured to perform or execute variousfunctions and operations of the thermal detection device. An output fromthe visual sensor and an output from the thermopile array are combinedby the controller or one of the plurality of additional modules togenerate a combined image for display.

In one embodiment, the invention provides a thermal detection devicethat includes an outer housing, a visual camera, a thermopile array, afirst control unit, a second control unit, and a display. The visualcamera is configured to generate a first signal related to a visualimage of a scene, and the thermopile array includes a plurality ofpixels. The first control unit is connected to the thermopile array andis configured to generate a second signal related to a thermal image ofthe scene. The second signal is associated with a temperature sensed byat least one of the plurality of pixels in the thermopile array, and thefirst control unit is positioned within a sub-housing. The sub-housingincludes at least one metallic side surface. The second control unit iselectrically connected to the visual camera and the first control unit.The second control unit is configured to receive a temperature signalrelated to a temperature of the thermopile array, and compensate thesecond signal based on the temperature signal. The display is configuredto display the visual image based on the first signal and the thermalimage based on the compensated second signal.

In another embodiment, the invention provides a thermal detection devicethat includes a visual camera, a thermopile array, a rechargeablelithium-based battery pack, a controller, and a display. The thermopilearray includes a plurality of pixels, and the rechargeable lithium-basedbattery pack is configured to be inserted into a handle portion of thethermal detection device for providing power to the thermal detectiondevice. The controller includes a processor and a memory. The controlleris configured to receive a first signal from the visual camera relatedto a visual image of a scene, receive a second signal from thethermopile array related to a thermal image of the scene and associatedwith a temperature sensed by at least one of the plurality of pixels inthe thermopile array, receive a temperature signal related to atemperature of the thermopile array, and compensate the second signalbased on the temperature signal. The display is configured to displaythe visual image based on the first signal and the thermal image basedon the compensated second signal.

Other aspects of the invention will become apparent by consideration ofthe detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1C illustrate a thermal detection device according to anembodiment of the invention.

FIG. 2 illustrates a thermal detection device according to anotherembodiment of the invention.

FIG. 3 is a perspective view of a battery pack according to anembodiment of the invention.

FIG. 4 is an exploded view of the battery pack of FIG. 3.

FIG. 5 is a top-view of the battery pack of FIG. 3.

FIG. 6 illustrates a thermal detection device according to anotherembodiment of the invention.

FIG. 7 illustrates is a schematic block diagram of a thermal detectiondevice according to an embodiment of the invention.

FIGS. 8-12 illustrate an assembly of thermal detector componentsaccording to an embodiment of the invention.

DETAILED DESCRIPTION

Before any embodiments of the invention are explained in detail, it isto be understood that the invention is not limited in its application tothe details of construction and the arrangement of components set forthin the following description or illustrated in the following drawings.The invention is capable of other embodiments and of being practiced orof being carried out in various ways.

Embodiments of the invention described herein relate to thermaldetection devices which detect and display a temperature characteristicof a scene. The thermal detection devices include a housing having adisplay portion, a user interface portion, a worklight portion, and atrigger portion. The thermal detection devices also include an opticsportion, a thermal detector, and a controller or control unit forreceiving signals from, among other things, the thermal detector, thetrigger portion, and the user interface portion, conditioning andprocessing the received signals, and outputting the conditioned andprocessed signals to, for example, the display portion, the worklightportion, and the thermal detector. The thermal detection devices arepowered by a removable and rechargeable battery pack which is connectedto a battery pack receiving interface of the housing. The thermaldetector is, for example, a thermopile array.

FIGS. 1A-1C illustrate a thermal detection device 100. The thermaldetection device 100 includes a housing 105 and a battery pack 110. Thehousing 105 includes a handle 115, a trigger portion 120, a worklightportion 125, a thermal sensor portion (see FIG. 7), a user input portion130, and a display portion 135. In some embodiments, the thermaldetection device 100 also includes a laser pointer. The laser pointer isprojected to, for example, the center of a detection area to aid theuser in locating the detection area.

FIG. 2 illustrates another thermal detection device 200. The thermaldetection device 200 is similar to the thermal detection device 100, andincludes a housing 205, a lens cover 210, and a battery pack 215. Thehousing 205 includes a handle 220, a trigger portion 225, a worklightportion 230, a thermal sensor portion (see FIG. 7), and a user input anddisplay portion 235. Embodiments of the invention described herein aredescribed with respect to the thermal detection device 100.

The thermal sensor portion includes, among other things, the thermalsensor, optics for the thermal detection device, and a visual sensor. Insome embodiments, the optics for the thermal detection device 100include a single selectable or focusable lens configuration. In otherembodiments, the optics for the thermal detection device 100 include adual lens configuration. The lenses are made of, for example, fluorite,silicon, Germanium, calcium fluoride, Chalcgenide, Zinc Sulfur, ZincSelenium, Sapphire, crown glass (e.g., BK-7), etc. In some embodiments,the optics for the thermal detection device are composed at least inpart of Aluminum. The lenses have a depth of focus of approximately 2-6feet. Dual lens configurations are implemented in embodiments of theinvention in which, for example, improved resolution is desired. In duallens embodiments, the inner lens is fixed, and the second lens is, forexample, an aspheric lens. Embodiments of the invention described hereinrelate to single lens implementations of the thermal detection device100.

The thermal sensor is, for example, a 32 pixel by 31 pixel (i.e., 32×31)thermopile array (i.e., thermal engine) positioned at the front end ofthe thermal detection device 100. As such, the thermopile arraygenerates signals corresponding to a thermal image that is 32 pixelswide and 31 pixels long. In some embodiments, the thermal detectiondevice 100 is not configured to provide absolute temperatures of ascene. In other embodiments, the thermal detection device 100 isconfigured to output absolute temperatures of a scene. The refresh rateof the thermal sensor is set to, for example, less than or equal to 9 Hzin accordance with government regulations. As is described in greaterdetail below with respect to a compensation module, the thermal sensoris highly sensitive to heat and temperature changes. In order toproperly compensate for this sensitivity, sensors are used to measuretemperature fluctuations caused by both internal and external heatsources.

The visual sensor is located at the front end of thermal detectiondevice 100 and below the thermal sensor. The visual sensor is covered bya clear plastic shield for protection. The visual sensor has aresolution of between, for example, 0.01 and 12 megapixels. In someembodiments, the thermal detection device 100 includes two or morevisual sensors. Images are captured by activating (e.g., depressing,releasing, holding, etc.) the trigger portion. In some embodiments, asingle image based on the thermal sensor and a single image based on thevisual sensor is captured at the time the trigger portion is activated.For example, each time the trigger portion is activated, a single visualimage is captured and a single thermal image is captured. Each image issaved as a separate file having, for example, a corresponding time-stampfor identification. In some embodiments, when the trigger portion isactivated, the image that is being displayed by the display portion iscaptured. In other embodiments, a series of images are captured based onthe amount of time that the trigger is activated. The visual sensor isalso configured for manual or automatic focusing and at least one of thevisual sensor module or controller (both described below) is configuredto execute one or more extended depth of focus (“EDOF”) techniques. Thevisual sensor refresh rate is approximately, for example, 30 Hz. Higherrefresh rates are possible for the visual sensor, but the perceptualeffects of the increase in refresh rate are virtually indistinguishableby the human eye.

The display portion 135 and user interface portion 130 include a visualdisplay and one or more user input devices (e.g., buttons),respectively. The visual display is, for example, a liquid crystaldisplay (“LCD”), a light-emitting diode (“LED”) display, an organic LED(“OLED”) display, an electroluminescent display (“ELD”), asurface-conduction electron-emitter display (“SED”), a field emissiondisplay (“FED”), or the like. In some embodiments, the display is a 3.5″thin-film transistor (“TFT”) LCD. In other embodiments, the display is aSuper active-matrix OLED (“AMOLED”) display. Displays are oftenrectangular in shape, and the outputs of the visual sensor or thermalsensor are often square in shape. As such, following the mapping of anoutput of a visual sensor or thermal sensor to the output display, thereare unused pixels around the edges of the display. The output of thevisual sensor, the output of the thermal sensor, or a combination of thetwo can be stretched to fit the screen. Additionally or alternatively,the unused pixels are black, or information is displayed in the unusedpixels (e.g., menus, temperature data, etc.). The refresh rate of thedisplay portion is approximately, for example, 30 Hz.

The housing 105 includes a battery pack interface within the handle 115of the thermal detection device 100 for connecting to the battery pack110. The battery pack 110 includes a casing 300, an outer housing 305coupled to the casing 300, and a plurality of battery cells 310 (seeFIG. 4) positioned within the casing 300. The casing 300 is shaped andsized to be at least partially received within the recess of the thermaldetection device handle 115 to connect the battery pack 110 to thethermal detection device 100. The casing 300 includes an end cap 315 tosubstantially enclose the battery cells 310 within the casing 300. Theillustrated end cap 315 includes two power terminals 320 configured tomate with corresponding power terminals of the thermal detection device100. In other embodiments, the end cap 315 may include terminals thatextend from the battery pack 110 and are configured to be received inreceptacles supported by the thermal detection device 100. The end cap315 also includes sense or communication terminals 325 (see FIG. 5) thatare configured to mate with corresponding terminals from the thermaldetection device 100. The terminals 325 couple to a battery circuit (notshown). The battery circuit can be configured to monitor various aspectsof the battery pack 110, such as pack temperature, pack and/or cellstate of charge, etc. and can also be configured to send and/or receiveinformation and/or commands to and/or from the thermal detection device100. In one embodiment, the battery circuit operates as illustrated anddescribed in U.S. Pat. No. 7,157,882 entitled “METHOD AND SYSTEM FORBATTERY PROTECTION EMPLOYING A SELECTIVELY-ACTUATED SWITCH,” issued Jan.2, 2007, the entire content of which is hereby incorporated byreference. In another embodiment, the battery circuit operates asillustrated and described in U.S. Pat. No. 7,589,500 entitled “METHODAND SYSTEM FOR BATTERY PROTECTION,” issued Sep. 15, 2009, the entirecontent of which is also hereby incorporated by reference.

The casing 300 and power terminals 320 substantially enclose and coverthe terminals of the thermal detection device 100 when the pack 110 ispositioned in the handle 115. That is, the battery pack 110 functions asa cover for the handle 115 and terminals of the thermal detection device100. Once the battery pack 110 is disconnected from the device 100 andthe casing is removed from the handle 115, the battery terminals on thethermal detection device 100 are generally exposed to the surroundingenvironment.

The outer housing 305 is integral with or coupled to an end of thecasing 300 substantially opposite the end cap 315 and surrounds aportion of the casing 300. In the illustrated construction, when thecasing 300 is inserted into, positioned within, or connected to thehandle 115 of the thermal detection device 100, the outer housing 305generally aligns with an outer surface of the handle 115. In thisconstruction, the outer housing 305 is designed to substantially followthe contours of the device 100 to match the general shape of the handle115 (e.g., the contours of the device 100 are complementary to contoursof the outer housing 305). In such embodiments, the outer housing 305generally increases (e.g., extends) the length of the handle 115 of thethermal detection device 100. The handle 115 is referred to as theportion of the thermal detection device 100 that is below the user inputportion 130.

In the illustrated embodiment, two actuators 330 (only one of which isshown) and two tabs 335 are formed in the outer housing 305 of thebattery pack 110. The actuators 330 and the tabs 335 define a couplingmechanism for releasably securing the battery pack 110 to the thermaldetection device 100. Each tab 335 engages a corresponding recess formedin the thermal detection device 100 to secure the battery pack 110 inplace. The tabs 335 are normally biased away from the casing 300 (i.e.,away from each other) due to the resiliency of the material forming theouter housing 305. Actuating (e.g., depressing) the actuators 330 movesthe tabs 335 toward the casing 300 (i.e., toward each other) and out ofengagement with the recesses such that the battery pack 110 may bepulled out of the handle 115 and away from the thermal detection device100. In some embodiments, the battery pack 110 is configured to beslidably attached to the housing 105. For example, the housing 105 caninclude a terminal that is configured to be engaged with a portion ofthe battery pack 110 such that the thermal sensor 100 is able to receivepower from the battery pack 110. In such embodiments, a portion of thebattery pack 110 is received in the housing 105 or a portion of thehousing 105 is received in the battery pack 110. In such embodiments,the battery pack 110 also includes a coupling mechanism having one ormore actuators 330 for releasably engaging the battery pack 110 and thehousing 105.

As shown in FIG. 5, the battery pack 110 includes three battery cells310 positioned within the casing 300 and electrically coupled to theterminals 320. The battery cells 310 provide operational power (e.g., DCpower) to the thermal detection device 100. In the illustratedembodiment, the battery cells 310 are arranged in series, and eachbattery cell 310 has a nominal voltage of approximately four-volts(“4.0V”), such that the battery pack 110 has a nominal voltage ofapproximately twelve-volts (“12V”). The cells 310 also have a capacityrating of approximately 1.4 Ah. In other embodiments, the battery pack110 may include more or fewer battery cells 310, and the cells 310 canbe arranged in series, parallel, or a serial and parallel combination.For example, the battery pack 110 can include a total of six batterycells 310 in a parallel arrangement of two sets of threeseries-connected cells. The series-parallel combination of battery cells310 creates a battery pack 110 having a nominal voltage of approximately12V and a capacity rating of approximately 2.8 Ah. In other embodiments,the battery cells 310 may have different nominal voltages, such as, forexample, 3.6V, 3.8V, 4.2V, etc., and/or may have different capacityratings, such as, for example, 1.2 Ah, 1.3 Ah, 2.0 Ah, 2.4 Ah, 2.6 Ah,3.0 Ah, etc. In other embodiments, the battery pack 110 can have adifferent nominal voltage, such as, for example, 10.8V, 14.4V, etc. Inthe illustrated embodiment, the battery cells 310 are lithium-ionbattery cells having a chemistry of, for example, lithium-cobalt(“Li—Co”), lithium-manganese (“Li—Mn”), Li—Mn spinel, or includingmanganese. In other embodiments, the battery cells 310 may have othersuitable lithium or lithium-based chemistries. In some embodiments, thethermal detection device 100 is powered by alkaline batteries such asAA, AAA, C, D, 9V, etc. batteries. The alkaline batteries can beconnected in series, parallel, or a series-parallel combination toachieve a desired voltage for the thermal detection device 100.

The battery pack 110 is also configured to connect and provide power toadditional devices such as drills, saws, grease guns, right angledrills, pipe cutters, lasers, impact wrenches, impact drivers,reciprocating saws, inspection cameras, radios, worklights,screwdrivers, wall scanners, infrared thermometers, clamp meters,digital multimeters, fork meters, multi-tools, grinders, band saws, jigsaws, circular saws, rotary hammers, generators, vacuums, etc.

In some embodiments, a battery pack controller is configured to provideinformation related to a battery pack temperature or voltage level to acontroller of the thermal detection device 100, such as the thermaldetection device controller 405 shown in and described with respect toFIG. 6. The thermal detection device controller 405 and the battery packcontroller also include low voltage monitors and state-of-chargemonitors. The monitors are used by the thermal detection devicecontroller 405 or the battery pack controller to determine whether thebattery pack 110 is experiencing a low voltage condition which mayprevent proper operation of the thermal detection device 100, or if thebattery pack 110 is in a state-of-charge that makes the battery pack 110susceptible to being damaged. If such a low voltage condition orstate-of-charge exists, the thermal detection device 100 is shut down orthe battery pack 110 is otherwise prevented from further dischargingcurrent to prevent the battery pack 110 from becoming further depleted.In some embodiments, the detection device 100 senses a voltageassociated with one or more cells of the battery pack 110 via the senseor communication terminal.

The thermal detection devices 100 and 200 described above areillustrated modularly as a thermal detection device 400 in FIGS. 6 and500 in FIG. 7. The shape and structure of the thermal detection devices400 and 500 is described above with respect to the thermal detectiondevices 100 and 200. The thermal detection device 400 generallyincludes, among other things, a controller 405, a display 410, and auser interface 415. The controller 405 is implemented on, for example,one or more printed circuit boards (“PCBs”). The PCBs are populated witha plurality of electrical and electronic components which provideoperational control and protection to the thermal detection device 400.In some embodiments, the PCBs include a control or processing unit 420such as a microprocessor, a microcontroller, or the like, a memory 425,an input/output (“I/O”) interface 430, and a bus. The bus connectsvarious components of the controller 405 including the memory to theprocessing unit. The memory 425 includes, for example, a read-onlymemory (“ROM”), random access memory (“RAM”) (e.g., dynamic RAM[“DRAM”], synchronous DRAM [“SDRAM”], etc.), electrically erasableprogrammable read-only memory (“EEPROM”), flash memory, a hard disk, anSD card, or other suitable magnetic, optical, physical, or electronicmemory devices. The controller 405 also includes an input/output systemthat includes routines for transferring information between componentswithin the controller 405. Software included in the implementation ofthe thermal detection device 400 is stored in the memory of thecontroller 405. The software includes, for example, firmwareapplications and other executable instructions. The processing unit 420is connected to the memory 425 and executes software instructions thatare capable of being stored in a RAM of the memory 425 (e.g., duringexecution), a ROM of the memory 425 (e.g., on a generally permanentbasis), or another non-transitory computer readable medium such asanother memory or a disc. In other embodiments, the controller 405 caninclude additional, fewer, or different components.

The PCB also includes, among other things, a plurality of additionalpassive and active components such as resistors, capacitors, inductors,integrated circuits, and amplifiers. These components are arranged andconnected to provide a plurality of functions to the PCB including,among other things, filtering, signal conditioning, and voltageregulation. For descriptive purposes, the PCB and the electricalcomponents populated on the PCB are collectively referred to as “thecontroller” 405. The controller 405 includes or receives signals fromthe sensors or components within the thermal detection device 100,conditions and processes the signals, and transmits processed andconditioned signals to, for example, the display.

With reference to FIG. 7 and thermal detection device 500, the thermaldetection device 500 includes a plurality of modules configured toprovide operative control to the thermal detection device 500. Themodules include, for example, hardware, software, or combinations ofhardware and software configured to achieve the desired function of eachmodule. As an illustrative example, each module can include hardware(e.g., electrical circuit components, displays, sensors, etc.) andsoftware (e.g., functions, subroutines, executable programs, etc.)associated with the functional and operative control of the module. Inthe embodiment of the invention illustrated in FIG. 7, the thermaldetection device 500 includes a variety of modules and componentsimplemented on one or more printed circuit boards (“PCBs”). For example,the thermal detection device 500 includes a main PCB 505 interconnectedwith a thermal sensor PCB 510, an environmental PCB 515A, anenvironmental PCB 515B, a visual sensor PCB 520, a display PCB 525, anda keypad PCB 530. Each PCB includes associated modules. For example, themain PCB 505 includes a main control unit 535, a universal serial bus(“USB”) module 540, a SDRAM memory module 545, a flash memory module550, a clock module 555, an oscillator module 560, a thermocouple module565, a keypad and battery control unit 570, and a battery module 575. Insome embodiments, the thermocouple module 565 is connected to another ofthe PCBs in the thermal detection device 500. The thermocouple 565 caninclude a cold junction sensor (e.g., a cold junction temperaturesensor). The thermal sensor PCB 510 includes a thermal sensor 580 and athermal sensor control unit 585. The environmental PCBs 515A and 515Beach include an ambient temperature sensor module 590, a humidity sensormodule 595, and a worklight module 600. The visual sensor PCB 520includes a visual sensor module 605. The display PCB 525 includes adisplay module 610, and the keypad PCB 530 includes a keypad module 615.Although the PCBs 510-530 are each illustrated as being separate fromand connected to the main PCB 505, in some embodiments of the invention,one or more of the PCBs 510-530 are integrated into the same PCB. Insome embodiments, the thermal detection device 500 includes threemicroprocessors (e.g., one connected to the thermal sensor PCB 510, oneconnected to the main PCB 505, and another connected to any one of thePCBs).

The battery module 575 is electrically connected to the battery pack 110for receiving power. The battery module 575 includes electricalcomponents (e.g., resistors, capacitors, diodes, transistors,amplifiers, etc.) to regulate and condition power for the variousmodules and components within the thermal detection device 500. Forexample, the battery module 575 is configured to produce a variety ofdifferent levels of voltage for the various modules and components ofthe thermal detection device 500 depending on the power requirements ofthe various modules and components. In some embodiments, the batterymodule 575 produces regulated and conditioned voltages betweenapproximately 0.7 volts and 12.0V.

Power from the battery module 575 is distributed to various modules andcomponents within the thermal detection device 500. In some embodiments,the battery module 575 continuously provides power to, for example, thecontrol unit 535 when the thermal detection device 500 is powered up(i.e., turned on). Additionally or alternatively, the battery module 575does not provide power to various modules or components until a signalfrom the control unit 570 or 535 indicating that power should besupplied to the module or components is received. For example, theworklight module 600 does not receive power from the battery module 575until the battery module 575 receives an indication from the controlunit 570 or 535 that the worklight module 600 is to receive power. Inother embodiments, the user activates or selects a button to open orclose a switch to provide power to one or more of the modules (e.g.,closing a switch to power the worklight module 600). The battery module575 can also be directly connected to various others of the modules orPCBs within the thermal detection device 500. The battery module 575 iscontrolled by the keypad and battery control unit 570. For example, thecontrol unit 570 can be configured to control a voltage or currentoutput of the battery module 575.

The keypad module 615 includes or receives signals from a plurality ofswitches (e.g., buttons) associated with the control and operation ofthe thermal detection device 500 (e.g., selecting temperature ranges fordisplay, selecting display colors or color palettes, selecting orsetting image review options, selecting operational modes, selectingdisplay modes, selecting displayed information, etc.). The switches arelocated in, for example, the user input portion 130. The keypad module615 includes, for example, a power button for turning the thermaldetection device 500 on and off, a review button for reviewing captureimages, a worklight button for turning the LED worklight on and off, atoggle button for toggling between a visual image display mode and ablended image display mode, a menu button for accessing one or moremenus of the thermal detection device 500, navigation buttons (e.g., up,down, left, right, etc.) for navigating through the one or more menus orstored images, a trigger for capturing images, and a select button formaking one or more selections from, for example, the one or more menus.In some embodiments, any of the above buttons can be combined such thata single button has multiple functions (e.g., the select button is alsoused to turn the thermal detection device 500 on and off, etc.).

As an illustrative example, the keypad module 615 receives signals fromthe trigger portion 120. The actuation or depression of the triggerportion 120 generates a signal which is received by the keypad module615 and is indicative of a desire to capture an image of a scene. Thekeypad module 615 sends the signal to the control unit 570 or 535 tocause the thermal image to be captured. Similarly, control buttonsrelated to the operational mode or display mode of the thermal detectiondevice 500 generate signals that are received by the keypad module 615.The keypad module 615 transmits the signals to the control unit 570 or535 to correspondingly control the operational or display mode of thethermal detection device 500. For example, the thermal detection device500 can include a “hot key” or toggle to switch between images that werecaptured using the thermal detection device 500. In some embodiments,the hot key is a physical button that is actuated to uni-directionallyscroll through captured images. In other embodiments, two or morebuttons are used to scroll through captured images in multipledirections (e.g., forward, reverse, etc.). To facilitate the review ofimages on the thermal detection device 500, the buttons can be used toaccess a folder or directory view of stored images which allows the userto access and view images which were previously captured using thethermal detection device 500. In some embodiments, the keypad module 615is included in or integrated with the display module 610 (e.g., when thedisplay module 610 includes a touch-screen display). The keypad module615 is also controlled by the keypad and battery control unit 570. Forexample, the control unit 570 can be configured to receive process,evaluate, and/or interpret signals received from the keypad module 615.

The visual sensor module 605 includes or receives signals from one ormore visual sensors as described above. The visual sensor module 605sends electrical signals corresponding to a sensed visual scene to thecontrol unit 535 for processing, or directly to the display module 610for display. The visual sensor module 605 receives power from thebattery module 575 and is configured to receive one or more controlsignals from the control unit 535. For example, the control unit 535provides the visual sensor module 605 with one or more signalscorresponding to settings of the one or more visual sensors. Thesettings of the visual sensors can include he ambient temperature. Suchan implementation prevents pixels from displaying extreme temperaturesand washing out images. In some embodiments, the blending is onlyperformed for portions of the scene within predefined temperature ranges(e.g., 40sual sensors in response. Alternatively, the control unit 535receives the signal from the thermal sensor 580 or control unit 585,determines what changes should be made to the operation of the visualsensor, and sends signals to the visual sensor module 605 to modify oneor more settings.

The thermal sensor control unit 585 receives signals from and transmitssignals to the thermal sensor 580. The signals received from the thermalsensor 580 include, for example, output signals related to the amount ofthermal radiation detected by the thermal sensor 580. The signalstransmitted by the thermal sensor control unit 585 to the thermal sensor580 include, for example, temperature compensation signals, as describedbelow. In some embodiments, the thermal sensor control unit 585 isconfigured to perform signal conditioning and processing on the outputsignals received from the thermal sensor 580. In other embodiments, andas described below, the signal conditioning and processing can also beperformed by the control unit 535. The signal conditioning andprocessing includes, among other things, upscaling (e.g.,interpolation), temperature compensation, normalization, etc. In someembodiments, the thermal sensor control unit 585 is included in thethermal sensor 580 or the control unit 535.

The display module 610 receives control signals from the control unit535 and power from the battery module 575 sufficient to illuminate, forexample, one or more LEDs or a display which provides an indication of aresult of a test. Among the signals received from the control unit 535are signals related to a display mode. For example, the display moduleis configured to operate in any of a variety of display modes, such as athermal image display mode, a visual image display mode, and a combineddisplay mode. The display module 610 is switched among the display modesby way of, for example, one or more control signals received by thekeypad module 615 (e.g., corresponding to one or more buttons beingpressed or switches being activated). The display module 610 isconfigured to remain in a selected display mode until the user activatesanother button or switch indicative of a desire to change the displaymode. Additional display modes include a review mode for reviewingcaptured images, and a menu mode in which one or more menus aredisplayed.

Included in the display are, for example, measured temperatures, averagetemperatures, ambient temperatures, indications of a detection area, adistance to a target, etc. The display also includes a crosshairpositioned at the center of the display. The crosshair is used as areference point within the displayed scene. A variety of additionaldisplay functions are based on the position of the crosshair in thedisplayed scene. For example, a temperature within a scene or an averagetemperature of a portion of the scene corresponding to the location ofthe crosshair is displayed on the display (e.g., in a corner of thedisplay). In some embodiments, a circle or square is drawn around thecrosshair which corresponds to, for example, approximately a 1.0° FOVabout the crosshair. In other embodiments, any of a variety of polygonsare used which correspond to a FOV about the crosshair. The polygonsurrounding the crosshair is indicative of the approximate sensed areafor the thermal sensor, or at least a portion of the sensed area forwhich a temperature can be reliably determined. Accordingly, the polygonis resized based on the distance of the thermal sensor from a targetwithin a scene. The approximate distance of the thermal sensor from thetarget within the scene is determined using, for example, a laserrangefinder or another similar distancing technique.

The ambient temperature sensor module 590 measures the ambienttemperature of the thermal detection device 500, the ambient temperatureof the thermal sensor 580, the thermal sensor PCB 510, a sub-housing 625(see FIGS. 8-12), the ambient temperature of the area surrounding thethermal detection device 500, and/or the ambient temperature of othercomponents of the thermal detection device 500 (e.g., one or more PCBs,etc.). The humidity sensor 595 measures the relative humidity of theenvironment surrounding the thermal detection device 500.

The worklight module 600 is connected to the worklight button describedabove. When the user activates the worklight button, a signal isprovided to the control unit 535. The control unit 535 selectivelyprovides power from the battery module 575 to the worklight module 600for illuminating the worklight portion 230.

The worklight portion 230 provides a convenient source of light whenoperating the thermal detection device 500, because the thermaldetection device 500 is sometimes used in dark environments; light fromthe worklight portion 230 can be used to provide sufficient illuminationfor the visual sensor(s). In some embodiments, the worklight includes anincandescent light bulb, one or more LEDs, or the like. In oneembodiment, the worklight includes three high-intensity LEDs and has anoutput of, for example, 250 LUX at a distance of two feet. As such, theworklight portion 230 is sufficiently powerful to illuminate an area infront of the thermal detection device 500. In some embodiments of theinvention, the output of the worklight is greater than 250 LUX at adistance of two feet.

The worklight portion 230 is either integral to or detachable from thethermal detection device 500. In embodiments of the invention in whichthe worklight portion 230 is detachable from the thermal detectiondevice 500, the worklight portion 230 includes a secondary power source,and the thermal detection device 500 and the worklight portion 230include corresponding interfaces for attachment and detachment (e.g.,flanges, tongues and grooves, magnets, etc.). The secondary power sourceis, for example, a battery that is electrically isolated from thethermal detection device 500, charged by the thermal detection device500, or otherwise receives power from the thermal detection device 500(e.g., wirelessly). The worklight also includes a worklight timeoutperiod. The worklight timeout period has a preprogrammed value or thevalue is set by the user. If the worklight timeout period is reached orlapses and the worklight portion 230 has not been turned off, theworklight portion 230 is turned off to conserve power. In someembodiments, the worklight portion 230 is positioned at the front end ofthe thermal detection device 500, is below the thermal sensor 580, andis covered by a clear plastic shield for protection.

The main PCB 505 includes one or more ports for, among other things,storing or retrieving data from the thermal detection device 500. Forexample, main PCB 505 includes one or more USB ports connected to orincluded in the USB module 540. Additionally or alternatively, the manPCB 505 includes one or more SD card slots, one or more FireWire ports,a serial port, a parallel port, etc., having corresponding modulesconnected to the control unit 535. In some embodiments, the thermaldetection device 500 includes an ability to transmit or receiveinformation over a wireless short-range communications network employinga protocol such as, for example, Bluetooth, ZigBee, Wi-Fi, or anothersuitable short-range communications protocol. The USB module 540 orflash memory module 550 allow a user to retrieve images stored in aninternal memory of the thermal detection device 500 and transfer themto, for example, a personal computer, phone, laptop, PDA, tabletcomputer, e-book reader, television, or the like. The images are storedas a file type such as JPEG, TIFF, PNG, GIF, BMP, etc. In someembodiments, the thermal detection device 500 includes a limited amountof memory, and a removable memory is inserted into the thermal detectiondevice 500 to store captured images. The flash memory can be removedfrom the thermal detection device 500 and inserted into a correspondingport on any of the previously mentioned devices. In some embodiments,the thermal detection device 500 is configured to capture still imagesand store them to the flash memory module 550 or another suitable memoryof the thermal detection device 500. In other embodiments, the thermaldetection device 500 is configured to capture still images and video ofa scene. In embodiments of the invention in which the flash memorymodule 550 is the only or primary storage medium, the absence of a flashmemory in the thermal detection device 500 may prevent the thermaldetection device 500 from being able to store images. In embodiments ofthe thermal detection device 500 that include both a flash memory slotand a USB port, and a flash memory is present in the flash memory module550, inserting a USB cable into the USB port can cause the images storedon the flash memory module 550 to be automatically downloaded to, forexample, a computer. The main PCB 505 also includes SDRAM in the SDRAMmodule 545, a clock in the clock module 555, and an oscillator in theoscillator module 560 for executing instructions stored in firmware ofthe control unit 535 during the operation of the thermal detectiondevice 500.

With continued reference to FIG. 7, the control unit 535 is configuredto perform a variety of compensation functions for the thermal detectiondevice 500. For example, the thermal sensor 580 is highly sensitive tovariations in temperature (e.g., ambient temperature). The pixels of thethermal sensor 580 also do not change uniformly. The pixels along theedges of the thermal sensor 580 have a tendency to be affected byvariations in ambient temperature more quickly than the pixels at theinterior of the thermal sensor 580. To compensate for these effects, thecontrol unit 535 includes (e.g., stores in a memory) or generates athermal map or a thermal gradient map for the thermal sensor 580. Themap corresponds to the manner in which each pixel of the thermal sensor580 is affected by variations in temperature. The map is then used tocompensate the output pixel values for each pixel of the thermal sensor580. In some embodiments, the control unit 535 detects a rate at whichthe ambient temperature of the thermal detection device 500 or theenvironment around the thermal detection device 500 is changing. Therate at which the ambient temperature is changing is used to modify, forexample, the rate at which the output of the thermal sensor 580 iscompensating, a thermal map that is being used for compensation, etc.

In some embodiments, the ambient temperature of the thermal detectiondevice 500, the ambient temperature of the thermal sensor 580, or thetemperature of one or more pixels of the thermal sensor 580 is adjustedby the control unit 535 such that it matches a temperature of a targetwithin a scene. Heat can be applied to each pixel in the thermal sensor580 or the peripheral pixels in the thermal sensor 580 to adjust thetemperature of the thermal sensor 580. In some embodiments, one or moreadditional temperature sensors are include within the thermal detectiondevice 500 to monitor the internal temperature of the thermal detectiondevice 500 (e.g., the temperature of the main PCB 505, the temperatureof the thermal sensor PCB 510, the internal ambient temperature of thethermal detection device 500, etc.). For example, an array oftemperature sensors are positioned around the thermal sensor 580 (e.g.,around the edges of the thermal sensor 580) to sense the temperature ofone or more pixels in the thermal sensor 580. The output signals fromthe temperature sensors are used to determine which portions of thethermal sensor 580 are different from the temperature of the targetwithin the scene. In some embodiments, the temperature sensors are usedin combination with a thermal gradient map for the thermal sensor 580 todetermine which portions of the thermal sensor 580 need to be heated orcooled to match the temperature of the target within the scene.Additionally or alternatively, the control unit 535 is configured tomatch the ambient temperature of the thermal detection device 500, theambient temperature of the thermal sensor 580, or the temperature of oneor more pixels of the thermal sensor 580 to an ambient temperature oraverage temperature of an environment near the thermal detection device500.

In some embodiments, a second thermopile array is used to source heat tothe thermal sensor and control the temperature of the thermal sensor580. Although additional power is required to, for example, supply heatto the thermal sensor 580 to match the temperature of the target withinthe scene, the use of a higher power battery pack 110 (e.g., 12V)enables the thermal detection device 500 to perform the temperaturematching without sacrificing other features or functions of the thermaldetection device 500.

The control unit 535 is also configured to perform a variety ofcalibration functions for the thermal detection device 500. For example,the control unit 535 has a memory that includes stored factorycalibration information for the thermal sensor. When the thermaldetection device 500 is turned on, a self calibration and warm up isexecuted. In some embodiments, the control unit 535 includes acombination of software and hardware for calibrating the thermal sensorduring use and without a shutter. In other embodiments, the control unit535 includes a combination of software and hardware for calibrating thethermal sensor during use and with the use of a shutter. For example, insome embodiments which do not include a shutter, the control unit 535computes calibration constants from raw calibration readings from thethermal sensor 580. The calibration constants can then be stored inmemory and recomputed for each new power cycle (e.g., after the thermaldetection device 500 is turned on).

Specifically, calibration points corresponding to 0° C., 5° C., 25° C.,30° C., 50° C., and 100° C. can be used to determine pixel gain valuesor constants that are used to determine temperatures within a scene andensure accurate temperature readings throughout the normal operatingtemperature range for the device. From these pixel gain values for thevarious calibration points, additional pixel gain values can beinterpolated by the main control unit 535 based on, for example, one ormore temperature readings (e.g., from the environmental PCBs 515A or515B and corresponding ambient temperature sensors). In someembodiments, one or more pairs of calibration points are used todetermine pixel gain values.

Additionally, in some embodiments, pixel gain has a strong dependence onthe location of the pixels on the thermopile array's surface. Forexample, the shape of the lens, aperture, and other optical elements canaffect the pixel gain values throughout the thermopile array. In someembodiments, the pixels located around the edges of the thermal sensorand in the corners of the thermal sensor also have lower signal-to-noiseratios than pixels in the center of the thermopile array. A mapping ofthe sensitivity of each or groups of pixels based on their location inthe thermopile array can be used to compensate for the differences insensitivity or signal-to-noise ratio in a similar manner as describedabove with respect to the thermal map.

Heat from, among other things, the thermal sensor control unit 585 andinternal and external voltage reference signals can also affect thereadings from the thermal sensor. For example, heat can affect thecolumn amplifier of the thermal sensor and result in artifacts beingpresent in the outputted thermal sensor data. The effects of the heat onthe column amplifier can be corrected in a variety of ways. For example,the pixel gain value at each temperature calibration point can beassumed to contain both an amplifier offset for the column and a pixelthermal offset. Alternatively, a common voltage, V_(COMMON), can besubtracted from the amplifier offset for the column and the pixelthermal offset readings. The amplifier offset for the column can then besubtracted from the pixel thermal offset to reduce the effects of columnelectrical drift.

The control unit 535 is also configured to perform additional functionsand processing related to the operation of the thermal detection device500. As described above, the user is able to select among a variety ofoperational modes, display modes, etc. The display modes include avisual sensor mode, a thermal sensor mode, and a blended mode. Theblended mode of operation combines signals received from the thermalsensor and signals received from the visual sensor into a combined orblended image which is capable of being displayed on the display. Thevisual sensor has a resolution of, for example, 160 pixels by 160 pixels(160×160). The thermal sensor (e.g., thermopile array) has a resolutionof, for example, 32 pixels by 32 pixels (32×32), 64 pixels by 64 pixels(64×64), 128 pixels by 128 pixels (128×128), less than 32 pixels by 32pixels, less than 64 pixels by 64 pixels, less than 128 pixels by 128pixels, less than 160 pixels by 160 pixels, etc. When combining thesignals from the visual sensor and the thermal sensor, the output of thethermal sensor can be up-scaled to match the size of the visual sensor(e.g., 160×160). The output of the thermal sensor 580 is up-scaled usingany of a variety of techniques, such as averaging of the closest datapoints, nearest neighborhood techniques, linear interpolation, pixelreplication, bilinear interpolation, bicupic interpolation, contraststretching, edge detection/enhancement, MTF peaking, integration, cubicconvolution, sync filters, bidirectional quadratic convolution, andcubic spline interpolation. The up-scaled output of the thermal sensor580 and the output of the visual sensor 605 can be combined or blendedin one or more of a variety of ways, such as, for example, a multiplyblend mode, a screen blend mode, overlay blend mode (e.g., visual imageis overlayed on top of thermal image), a U-shaped or parabolic blendmode (e.g., to under-emphasize neutral temperatures near an ambienttemperature), a soft light blend mode, a hard light blend mode, a dodgeblend mode, a color dodge blend mode, a linear dodge blend mode, a burnblend mode, a color burn blend mode, a linear burn blend mode, a divideblend mode, an addition blend mode, a subtraction blend mode, adifference blend mode, a darken only blend mode, etc. Contrastenhancement can also be performed on the visual and thermal images toincrease the quality of the displayed image. In some embodiments, asoftware offset registration can be performed by the control unit 535 toensure that the visual image and the thermal image are properly alignedfor blending. For example, Bresenham's line algorithm can be used ormodified to by the control unit 535 to correct for pixel offset. In someembodiments, sequential programming is used in place of a programmablelogic device to generate a blended thermal image for display on thedisplay 610 of the thermal detection device 500.

In some embodiments, each pixel in the output of the visual sensor 605and each pixel in the up-scaled output of the thermal sensor 580 isassigned a numerical value corresponding to an 8-bit color (i.e., avalue between 0 and 255). The values for each pixel of the output fromthe visual sensor and the values for each pixel of the up-scaled outputof the thermal sensor 580 are then proportioned, combined, andnormalized to generate an output image signal.

In other embodiments, different normalization techniques can be used.For example, only pixels corresponding to temperatures within, forexample, a +/−5° or +/−10° window around the ambient temperature aredisplayed. The ambient temperature sensor 590 is used to determine theambient temperature of a scene being imaged or the ambient temperatureof the environment around the thermal detection device 500. The outputpixel values are then scaled such that all colors correspond to thewindow around the ambient temperature. Such an implementation preventspixels from displaying extreme temperatures and washing out images. Insome embodiments, the blending is only performed for portions of thescene within predefined temperature ranges (e.g., 40°-80°), or only theportions of a scene within a predefined or predetermined FOV of thethermal sensor are blended. In other embodiments, a similarnormalization procedure is performed, but an average temperature of ascene is determined (e.g., either an actual average temperature or anaveraging of the pixel values for the output of the thermal sensor).Although the display colors are generally displayed according to thevisual color spectrum (i.e., from red to blue or violet), in someembodiments, the user is able to adjust or modify the colors at whichcertain temperatures or pixel values are displayed.

In some embodiments, the control unit 535 precomputes or stores a colormap that is used to generate a thermal image. For example, the color mapis a square array of 32 colors, 64 colors, 128 colors, 256 colors, etc.A value for the visual intensity of a pixel is determined based onsignals from the visual sensor 605, a value for the thermal intensity isdetermined based on signals from the thermal sensor 580, and the twovalues are used to look up a corresponding color. In such animplementation, the color map can replace mathematical calculations fordetermining a corresponding pixel display color.

FIGS. 8-12 illustrate a thermal sensor assembly 620. The thermal sensorassembly 620 includes the main PCB 505, the thermal sensor PCB 510, thethermal sensor 580, the visual sensor 605, the keypad PCB 530, thevisual sensor PCB 520, environmental PCBs 515A and 515B, thethermocouple 565, and the display PCB 525 or LCD panel. In theillustrated embodiment, the thermal sensor 580 is positioned forward ofand parallel to the thermal sensor PCB 510. The thermal sensor 580 andthe thermal sensor PCB 510 are connected to or located at leastpartially within a housing or a sub-housing 625. The sub-housing 625encloses the thermal sensor PCB 510 and is made of metal, such asaluminum (e.g., the sub-housing is wholly made of metal, each sidesurface of the sub-housing is made of metal, at least one side surfaceof the sub-housing is made of metal, at least two side surfaces of thesub-housing are made of metal, etc.). In some embodiments, the main PCB505 is enclosed within the same sub-housing 625 as the thermal sensorPCB 510. In other embodiments, the main PCB 505 and the thermal sensorPCB 510 are included in different sub-housings (e.g., different metalsub-housings). As such, the housing 625 functions as a heat sink todissipate heat generated by the thermal detection device and stabilizethe temperature of the thermal sensor 580 and the internal temperatureof the thermal detection device 500. In other embodiments, the housing625 is partially or wholly made of plastic.

The visual sensor 605 is positioned above the thermal sensor 580. Thevisual sensor PCB 520 is positioned or located above the thermal sensor580 and the visual sensor 605. The visual sensor PCB 520 isapproximately perpendicular to the thermal sensor PCB 510 and thehousing 625. The environmental PCB 515A is positioned above andapproximately parallel to the visual sensor PCB 520, and theenvironmental PCB 515B is positioned below and approximately parallel tothe visual sensor PCB 520. The main PCB 505 is positioned or locatedbehind (e.g., spaced apart from) the thermal sensor 580 and thesub-housing 625. In the illustrated embodiment, the main PCB 505 formsan acute angle with respect to the thermal sensor PCB 510. The anglebetween the thermal sensor PCB 510 and the main PCB 505 is, for example,between approximately 0° (e.g., +/−)3° and approximately 30° (e.g.,+/−)3°. In other embodiments, the main PCB 505 is approximately orsubstantially parallel to the thermal sensor PCB 510. The main PCB 505is connected to the display PCB 525 to provide drive signals to thedisplay PCB 525. For example, the main PCB 505 provides one or moreimage or video signals related to a scene (e.g., an environmentsurrounding the thermal detection device 500), one or more signalsrelated to a measured characteristic of the scene (e.g., a temperature),one or more signals related to a status of the thermal detection device500, etc. The signals from the main PCB 505 are then used to generate avisual display corresponding to the signals and for a user to view. Inthe illustrated embodiment, the display PCB 525 is approximately orsubstantially parallel to the main PCB 505. For example, the anglebetween the display PCB 525 and the main PCB 505 is, for example,between approximately 0° (e.g., +/−3°) and approximately 30° (e.g.,+/−3°). In other embodiments, the display PCB 525 is approximately orsubstantially parallel to the main PCB 505 (e.g., +/−3°).

Also included between the main PCB 505 and the display PCB 525 is thethermocouple 565. The thermocouple 565 is connected to the main PCB 505to provide signals related to a contact temperature measurement of anobject or scene. The keypad PCB 530 is positioned or located below thedisplay PCB 525 and the main PCB 505. The keypad PCB 530 includes avariety of user inputs (e.g., buttons) as described above. The keypadPCB 530 and forms an obtuse angle with respect to the display PCB 525.The angle between the keypad PCB 530 and the display PCB 525 is between,for example, approximately 90° (e.g., +/−3°) and approximately 180°(e.g., +/−3°). The angle between the keypad PCB 530 and the display PCB525 enhances the operation of the thermal detection device 500 byallowing a user to view the display portion 135 and operate the userinput portion 130 while gripping the thermal detection device 500 in onehand and inspecting the scene.

Thus, the invention provides, among other things, a thermal detectiondevice that includes a visual sensor, a thermal sensor, and a display.Various features and advantages of the invention are set forth in thefollowing claims.

What is claimed is:
 1. A thermal detection device comprising: an outerhousing; a visual camera configured to generate a first signal relatedto a visual image of a scene; a thermopile array including a pluralityof pixels; a first control unit connected to the thermopile array andconfigured to generate a second signal related to a thermal image of thescene, the second signal associated with a temperature sensed by atleast one of the plurality of pixels in the thermopile array, the firstcontrol unit positioned within a sub-housing, the sub-housing includingat least one metallic side surface; a second control unit electricallyconnected to the visual camera and the first control unit, the secondcontrol unit configured to receive a temperature signal related to atemperature of the thermopile array, and compensate the second signalbased on the temperature signal; and a display configured to display thevisual image based on the first signal and the thermal image based onthe compensated second signal.
 2. The thermal detection device of claim1, wherein a removable and rechargeable battery pack is configured to beinserted into a handle portion of the outer housing for providing powerto the thermal detection device.
 3. The thermal detection device ofclaim 1, wherein the second signal is compensated based on a thermal mapof the plurality of pixels in the thermopile array.
 4. The thermaldetection device of claim 1, wherein the thermopile array has aresolution of less than or equal to 160 pixels by 160 pixels.
 5. Thethermal detection device of claim 4, wherein the thermopile array has aresolution of less than or equal to 64 pixels by 64 pixels.
 6. Thethermal detection device of claim 1, wherein the thermal detectiondevice does not include a shutter.
 7. The thermal detection device ofclaim 6, wherein one of the first control unit and the second controlunit is further configured to access, from memory, a pixel gain valuefor each of the plurality of pixels within the thermopile array.
 8. Thethermal detection device of claim 7, wherein one of the first controlunit and the second control unit is further configured to calculate newpixel gain values for each of the plurality of pixels within thethermopile array based on the accessed pixel gain values and a conditionof the thermal detection device.
 9. The thermal detection device ofclaim 8, wherein the condition of the thermal detection device is thetemperature related to the thermopile array.
 10. The thermal detectiondevice of claim 6, further comprising a thermocouple operable for makingcontact temperature measurements.
 11. The thermal detection device ofclaim 1, wherein the sub-housing is positioned substantially within theouter housing.
 12. The thermal detection device of claim 11, whereineach side surface of the sub-housing is metallic.
 13. The thermaldetection device of claim 1, wherein the at least one metallic sidesurface is made of aluminum.
 14. The thermal detection device of claim1, further comprising a first ambient temperature sensor positionedabove the sub-housing, and a second ambient temperature sensorpositioned below the sub-housing, the first ambient temperature sensorproviding the temperature signal to the second control unit, the secondambient temperature sensor providing a second temperature signal to thesecond control unit.
 15. A thermal detection device comprising: a visualcamera; a thermopile array including a plurality of pixels; arechargeable lithium-based battery pack configured to be inserted into ahandle portion of the thermal detection device for providing power tothe thermal detection device; a controller including a processor and amemory, the controller configured to receive a first signal from thevisual camera related to a visual image of a scene, receive a secondsignal from the thermopile array related to a thermal image of thescene, the second signal associated with a temperature sensed by atleast one of the plurality of pixels in the thermopile array, receive atemperature signal related to a temperature of the thermopile array, andcompensate the second signal based on the temperature signal; and adisplay configured to display the visual image based on the first signaland the thermal image based on the compensated second signal.
 16. Thethermal detection device of claim 15, wherein the thermal detectiondevice does not include a shutter.
 17. The thermal detection device ofclaim 16, wherein the controller is further configured to access, frommemory, a pixel gain value for each of the plurality of pixels withinthe thermopile array.
 18. The thermal detection device of claim 17,wherein the controller is further configured to calculate new pixel gainvalues for each of the plurality of pixels within the thermopile arraybased on the accessed pixel gain values and a condition of the thermaldetection device.
 19. The thermal detection device of claim 18, whereinthe condition of the thermal detection device is the temperature relatedto the thermopile array.
 20. The thermal detection device of claim 15,wherein the thermopile array has a resolution of less than or equal to32 pixels by 32 pixels.